Transrectal ultrasonography-guided biopsy does not reliably identify dominant cancer location in men with low-risk prostate cancer.

OBJECTIVE To evaluate the ability of transrectal ultrasonography (TRUS)-guided extended core biopsy to identify the dominant tumour accurately in men with early stage prostate cancer. PATIENTS AND METHODS Patients with early stage, low-risk prostate cancer who subsequently underwent radical prostatectomy (RP) and had complete surgical specimens were identified. Re-review was performed by a single uropathologist using ImageJ software to identify tumour location, dominant grade (DG) and dominant volume (DV). Pathology findings were then compared with biopsy results. RESULTS A total of 51 men with early stage, low-risk prostate cancer, who had undergone RP, had complete specimens for review and a median of 15 biopsy cores taken for diagnosis and grading. Sixteen men had a single diagnostic biopsy, 21 had one repeat biopsy, and 14 had two or more repeat biopsies. Compared with surgical findings, biopsy correctly identified the sextant with the largest tumour volume in 55% (95% CI 0.5-0.6) of specimens and the highest grade in 37% (95 CI 0.3-0.5). No demographic or clinical factors were significantly associated with identification of DG. Interval between last biopsy and RP, total tissue length taken and total length of tumour identified were significantly associated with correct identification of DV. CONCLUSIONS Our findings show that TRUS-guided biopsy detects and localizes DV better than it does DG. Even with an extended scheme, TRUS-guided biopsy does not reliably identify dominant cancer location in this low-risk cohort of men with early stage prostate cancer. TRUS-guided biopsy may perform better in similar men with low stage, but higher volume disease.